# std::remove_extent

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< cpp‎ | types

Defined in header `<type_traits>` |  |
template< class T > struct remove_extent; |  | (since C++11)

If `T` is an array of some type `X`, provides the member typedef `type` equal to `X`, otherwise `type` is `T`. Note that if T is a multidimensional array, only the first dimension is removed.

If the program adds specializations for `std::remove_extent`, the behavior is undefined.

### Member types

Name | Definition
`type` | the type of the element of `T`

### Helper types

template< class T > using remove_extent_t = typename remove_extent<T>::type; |  | (since C++14)

### Possible implementation

    template<class T>
    struct remove_extent { using type = T; };

    template<class T>
    struct remove_extent<T[]> { using type = T; };

    template<class T, std::size_t N>
    struct remove_extent<T[N]> { using type = T; };

### Example

Run this code

    #include <algorithm>
    #include <iostream>
    #include <iterator>
    #include <type_traits>

    template<class A>
        std::enable_if_t<std::rank_v<A> == 1>
    print_1d(const A& a)
    {
        std::copy(a, a + std::extent_v<A>,
            std::ostream_iterator<std::remove_extent_t<A>>(std::cout, " "));
        std::cout << '\n';
    }

    int main()
    {
        int a[][3] = {{1, 2, 3}, {4, 5, 6}};
    //  print_1d(a); // compile-time error
        print_1d(a[1]);
    }

Output:

    4 5 6

### See also

is_array (C++11) | checks if a type is an array type (class template)
rank (C++11) | obtains the number of dimensions of an array type (class template)
extent (C++11) | obtains the size of an array type along a specified dimension (class template)
remove_all_extents (C++11) | removes all extents from the given array type (class template)

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